I was just figuring a person could keep the cab fastened for better alignment. Right now I have my cab bolted on a front piece of frame from a junked AD truck. I replaced the floor pan (from seat to toe pan,part of the cab mount,inner to outer, and the outer cowl panel to just short of the lead line of the cab and the toe pan from the a level even with the top of the inner to outer down and across about 4-5" up from the floor (an L-shaped piece. Also cut out and replaced the top portion of the rocker that was under the lip of the floor pan. Still need to weld in an inner cowl panel.
The passenger's side will need pretty much the same thing, I think I'll replace the whole cab mount, and I need to replace the front lower portion of the door jam lip.
Cab corners for both sides and an inner cab corn for one side.
Like someone else said, rust isn't fun, one thing leads into another.....
John